This invention relates to an improved flexible coupling for connecting driving and driven members and, more particularly, to an improved coupling useful with appliances such as automatic washing machines, for example.
It is often desired to connect a rotary driving member to a rotary driven member under circumstances where the axes of the two members are not aligned. They may be misaligned laterally or they may be canted with respect to each other. Additionally the straight line distance between the points of attachment to the two members may be variable. The rotary transmission problems are more severe when vibration or other movement of one or both of the driving and driven members causes the orientation and spacing of these members to change during operation.
An example of such a situation is an automatic clothes washing machine. Such machines customarily proceed through a sequence of operations or cycles in order to wash, rinse and then spin dry fabrics. A typical machine has a stationary tub, a clothes retaining basket, and a vertical axis vaned agitator. During the wash and rinse operations the agitator is oscillated back and forth while the clothes retaining basket is prevented from movement. In the spin dry or liquid extraction operations the basket and agitator are rotated or spun in unison at high speed to extract liquid from the clothes by centrifugal force. During wash and rinse operations a pump constantly recirculates the washing liquid through a filter to remove lint and other contaminants. During the liquid extraction operations the pump operates to remove washing liquid from the machine.
It is desirable that all of these operations be accomplished by use of a single motor. To this end the washing machine normally includes a transmission for providing oscillation of the agitator during washing and rinsing operations and rotation of the agitator and basket during the spin or liquid extraction operation. Normally the transmission is driven by an endless belt which, in turn, is driven by a reversible electric motor through a clutch mechanism. The motor also drives the pump. The connection between the motor and the pump must be flexible to accommodate various positions that the motor may assume relative to the pump, axially, laterally and angularly. Additionally this coupling must be able to accommodate movement between the pump and motor as the pump normally is attached to the stationary tub while the motor is part of the moving system of the machine and tends to vibrate during operation.
U.S. Pat. No. 4,031,715, assigned to General Electric Company, assignee of the present invention, is illustrative of a prior art approach to the connection between the motor and the pump in an automatic washing machine. It utilizes a one-piece flexible plastic molded body which is attached to the motor output shaft and to the pump input shaft. The body is provided with a number of longitudinally extending slits dividing it into a plurality of fingers which are bowed as the coupling is attached to the machine. The very large number of fingers tends to cause the pump to be driven at a uniform speed, as the average length of the fingers tends to remain constant despite relative motion of the clutch with respect to the pump. However, collars of this type are relatively stiff and tend to resist relative movement between the clutch and the pump and tend to cause some variations in the pump speed.
It is an object of the present invention to provide a new and improved flexible coupling.
It is another object of this invention to provide such an improved coupling which transmits rotary motion from a driving to a driven member in a substantially uniform manner.
It is yet another object of this invention to provide such an improved coupling which compensates for variations in the alignment of the driving and driven members occurring during operation.